The production of solar salt from seawater by evaporation through solar action is well known and in widespread commercial use. Conventionally, such solar salt installations comprise a series of open ponds into which seawater is introduced and the concentration of the salt in the brine progressively increases toward the last pond, called the crystallizer, in which sodium chloride crystals are recovered. After several months of operation, the salt crop in the last crystallizer pond increases to a desired depth whereby the brine is drained from the pond and heavy equipment such as earth movers or the like are employed for scraping and removing the solid salt crop. The use of such heavy equipment and the scraping action along the floor or bottom of the pond invariably results in a contamination of the salt crop with sand, earth and clay defining the bottom of the pond structure necessitating subsequent purification of the harvested crop prior to use. A further disadvantage associated with such prior art conventional harvesting techniques has been the necessity of draining the protective overlying brine layer from the pond exposing the salt crop to precipitation which has resulted in some instances, with a loss of all or substantial portions of the crop due to redissolution thereof as a result of heavy rainfalls.
The present invention is directed to an improved salt harvester for harvesting a salt crop from a solar crystallizer in a manner whereby the salt crop is continuously protected by an overlying brine layer and wherein the harvesting is effected so as to retain a residual salt floor over the bottom of the crystallizer and avoiding contamination of the harvested salt crop with earth, sand and clay of which the crystallizer is constructed. The present invention is particularly applicable for the harvesting of salt crops from solar crystallizers of the types described in copending U.S. patent application Ser. No. 622,475, filed June 20, 1984 by John F. Heiss and Melvin E. Leverenz and entitled "Solar Salt Crystallizer and Process for Producing Salt", now U.S. Pat. No. 4,564,367, granted Jan. 14, 1986, which is assigned to the assignee of the present invention. The teachings as set forth in the aforementioned copending application are incorporated herein by reference to facilitate a further understanding of the present invention.